FIELD OF THE INVENTION
The present invention relates generally to an apparatus and method for performing a thermal therapy patient treatment protocol. More particularly, the invention relates to a novel apparatus and method for physically separating organs to enable aggressive thermal therapy to be administered safely and relatively comfortably, on an outpatient basis, if desired.
Thermal therapy has been proven to be an effective method of treating various human tissues. Thermal therapy includes tissue freezing, thermotherapy, hyperthermia treatment and various cooling treatments. Thermotherapy treatment is a relatively new method of treating cancerous, diseased and/or undesirably enlarged human prostate tissues. Hyperthermia treatment is well known in the art, involving the maintaining of a temperature between 41.5 degrees Celsius through 45 degrees Celsius. Thermotherapy, on the other hand, usually requires energy application to achieve a temperature above 45 degrees Celsius for the purposes of coagulating the target tissue. Tissue coagulation beneficially changes the density of the tissue. As the tissue shrinks, forms scars and is reabsorbed, the impingement of the enlarged tissues, such as an abnormal prostate, is substantially lessened. Further, tissue coagulation and its beneficial effects are useful for treating cancerous tissue, because cancer cells are particularly susceptible to abnormal temperatures. Cancer cells can be treated in accordance with the present invention with temperatures in excess of 100 degrees Celsius without damage to the therapy applicator or discomfort to the patient.
The higher temperatures required by thermotherapy require delivery of larger amounts of energy to the target prostate tissues. At the same time, it is important to protect nontarget tissues from the high thermotherapy temperatures used in the treatment. Providing safe and effective thermal therapy, therefore, requires devices and methods which have further capabilities compared to those which are suitable for hyperthermia.
Although devices and methods for treating prostate cancer and benign prostatic hyperplasia have evolved dramatically in recent years, significant improvements have not occurred and such progress is badly needed. As recently as 1983, medical textbooks recommended surgery for removing cancerous or impinging prostatic tissues and four different surgical techniques were utilized. Suprapubic prostatectomy was a recommended method of removing the prostate tissue through an abdominal wound. Significant blood loss and the concomitant hazards of any major surgical procedure were possible with this approach.
Perineal prostatectomy was an alternatively recommended surgical procedure which involved gland removal through a relatively large incision in the perineum. Infection, incontinence, impotence or rectal injury were more likely with this method than with alternative surgical procedures.
Transurethral resection of the prostate gland has been another recommended method of treating benign prostatic hyperplasia. This method required inserting a rigid tube into the urethra 15. A loop of wire connected with electrical current was rotated in the tube to remove shavings of the prostate at the bladder orifice. In this way, no incision was needed. However, strictures were more frequent and repeat operations were sometimes necessary.
The other recommended surgical technique for treatment of benign prostatic hyperplasia was retropubic prostatectomy. This required a lower abdominal incision through which the prostate gland was removed. Blood loss was more easily controlled with this method, but inflammation of the pubic bone was more likely.
With the above surgical techniques, the medical textbooks noted the vascularity of the hyperplastic prostate gland and the corresponding dangers of substantial blood loss and shock. Careful medical attention was necessary following these medical procedures.
The problems previously described led medical researchers to develop alternative methods for treating prostate cancer and benign prostatic hyperplasia. Researchers began to incorporate heat sources in Foley catheters after discovering that enlarged mammalian tissues responded favorably to increased temperatures. Examples of devices directed to treatment of prostate tissue include U.S. Pat. No. 4,662,383 (Harada), U.S. Pat. No. 4,967,765 (Turner), U.S. Pat. No. 4,662,383 (Sogawa) and German Patent No. DE 2407559 C3 (Dreyer). Though these references disclosed structures which embodied improvements over the surgical techniques, significant problems still remain unsolved.
Recent research has indicated that cancerous and/or enlarged prostate glands are most effectively treated with higher temperatures than previously thought. Complete utilization of this discovery has been tempered by difficulties in protecting rectal wall tissues from thermally induced damage. While shielding has been addressed in some hyperthermia prior art devices, the higher energy field intensities associated with thermotherapy necessitate devices and methods having further capabilities beyond those suitable for hyperthermia. For example, the microwave-based devices disclosed in the above-referenced patents have generally produced relatively uniform cylindrical energy fields. Even at the lower energy field intensities encountered in hyperthermia treatment, unacceptably high rectal wall temperatures have limited treatment periods and effectiveness.
The prostate lies immediately above the rectum. The two structures are separated only by a thin fascial plane called the Denonvillier's fascia. This is composed of two layers which are in close contact. To kill prostate cancer cells within the prostate, the entire prostate, including the peripheral zone, must be included in the thermal window. However, because the rectum lies in intimate contact with the prostate, if one were to direct enough noxious agents, in most methods heat, to the periphery of the prostate sufficient to kill the cancer cells, one risks additionally damaging the adjacent rectum. This is the problem that the previously known methods have, which leads either to failure of treatment or morbidity.
In addition, efficient and selective cooling (for heat-based treatments) or warming (for freezing treatments) of the devices is rarely provided. This substantially increases patient discomfort and increases the likelihood of healthy tissue damage during benign prostatic hyperplasia treatments. These problems have necessitated complex and expensive temperature monitoring systems along the urethral wall. Satisfactory ablative prostate cancer therapy using extremely high or low temperature treatments cannot be undertaken without effective thermal control of the therapy device including effective cooling of exterior portions of the therapy device.
It would therefore be useful to utilize a method of treatment which enables the physician to both protect the adjacent rectum while still enabling the physician to direct enough heat to sufficiently kill the cancer cells.